Streamlined strategy for discovering active compounds for nephrolithiasis treatment from herbal medicines using the fruit fly model

ETHNOPHARMACOLOGICAL RELEVANCE: Traditional Chinese medicines (TCMs) show promise for treating nephrolithiasis (kidney stones) with fewer adverse effects. However, identifying the key active compounds and understanding the therapeutic mechanisms of these herbs is challenging due to their complex compositions. Utilizing appropriate animal models is essential for overcoming this challenge and investigating the underlying mechanisms. AIM OF THE STUDY: This study aims to establish a rapid discovery strategy to identify novel active components from TCMs using a Drosophila melanogaster (fruit fly) model. MATERIALS AND METHODS: A discovery strategy for novel active components from candidate TCMs for the treatment of kidney stones was established using a fruit fly kidney stone model. The model was developed by feeding flies sodium oxalate (NaOx) to induce crystallization in their Malpighian tubules (MTs). Water extracts from various TCMs were screened for their efficacy against kidney stones. Effective extracts were then fractionated using solid-phase extraction and re-evaluated with the fruit fly model. These effective fractions were further analyzed using LC-MS and NMR to identify their compositions, and the identified compounds underwent additional testing with the fruit fly model to pinpoint the core active compounds. DHE staining, RT-qPCR, and in vitro crystallization assays were employed to explore the therapeutic mechanisms of both the effective TCM extracts and their core compounds, ensuring consistency in their mechanisms within the fly model. Finally, the efficacy of the core compounds was validated in a glyoxalate-induced mouse model. RESULTS: In this study, a calcium oxalate kidney stone model was established using fruit fly. Three TCMs-Honghua (HH), Danshen (DS), and Huangqi (HQ)-were identified for their therapeutic effects against kidney stones from 15 candidates using the fruit fly model. The core compounds discovered were Hydroxysafflower yellow A (HYA) from HH, Salvianic acid A (SAA) from DS, and Calycosin-7-O-β-D-glucoside (CG) from HQ. HYA, SAA, and CG all demonstrated efficacy by inhibiting crystallization and reducing oxidative stress. Additionally, CG was also found to increase diuresis. The therapeutic effects of HYA, SAA, and CG were further validated in the mouse model. CONCLUSION: We developed an efficient strategy for identifying core components of TCMs for kidney stones treatment using a fruit fly model combined with chemical isolation and identification techniques. This approach led to the discovery of three novel potential compounds for controlling kidney stones. Validated in mammalian models, these findings underscore the fruit fly model's utility in uncovering bioactive substances from TCMs, laying the groundwork for future research and the development of novel kidney stones therapies.